CMU's robots are called STRIDE, for Surface Tension based Robotic Insect Dynamic Explorer. They mimic the way water strider insects "walk" on water.
I wanted to see how difficult it is to make a "robot" that moves on top of the water surface, purely based on surface tension. I found out that recreating the principle is not hard at all.
When carefully putting the construction on the water, the surface tension keeps it on top. When disturbed, the construction sinks, proving it is really the surface tension that does the trick.
The vibration of pager motor gives it some rudimentary propulsion (both on land and on water actually).
I hope this experiment inspires you and I look forward to hear what you can do with it. And of course, your vote is welcome.
Step 1: Materials
A test showed that the small diameter carbon fiber reinforced rods work fine. You can find these "carbon" rods at modeling shops stocking indoor flying materials. I used two 0.8mm diameter rods, about 1 m in length. The more commonly available 1 mm diameter rods are probably also worth a try.
The other materials used are:
A small a pager motor
A small 1.5V button cell battery
Some scotch tape
A tiny piece of double sided tape
Step 2: Basic construction
Step 3: Further devellopment
With the nice ripple pattern generated, the construction makes a simple kinetic art bot. In a next stage, the principle could form the basis for an aquatic BEAM, by adding some sensory input controlling two differently oriented pager motors. You can compensate for the extra weight (we are talking of grams of course) by adding extra carbon fiber rods.